Our long range goals remain to develop the tools to understand at the molecular level the mechanisms responsible for temporal expression and cellular differentiation in Bacillus subtilis. Gene fragments have been isolated from B. subtilis by use of restriction enzymes and plasmids. To pursue this approach we will continue to concentrate on obtaining a genetically marked B. subtilis plasmid. As an alternative we will continue to investigate the B. subtilis phage SPO2 as a molecular vehicle for cloning of DNA of B. subtilis. Either of these approaches will allow us to do direct screening for sporulation markers as well as complementation analysis of B. subtilis genetic markers as well as to provide reagents for assay of mRNA fractions at intervals during development. BIBLIOGRAPHIC REFERENCES: Specialized Transduction in Bacillus subtilis. D.H. Dean, K. Hutchison and H.O. Halvorson. Microbiol. 1976, in press.